1. Field of the Invention
The present invention relates to the capture, storage, and retrieval of digital images. More particularly, the present invention relates to novel methods for storing and retrieving pixel data from a full-color RGB imaging array imbedded in a device such as a digital camera.
Furthermore, the present invention also relates to active pixel sensors and active pixel sensor arrays. More particularly, the present invention relates to arrays of active pixel sensors wherein each of the active pixel sensors is a triple-junction structure to ensure that each pixel sensor in the array measures each of the three primary colors (R-G-B) in the same location.
Finally, the present invention relates to a device such as a digital camera that employs both a triple-junction active pixel sensor array and a novel method of capturing, storing, and retrieving the data provided by the array.
2. The Prior Art
The process of capturing, processing, storing, and retrieving digital data is common in the field of digital imaging.
Generally, a digital image is provided from a source, such as a camera. Many types of cameras are prevalent in the field of digital imaging, including digital, video, and television cameras. Whatever the type of camera used, it is often desired that the image be captured and stored in a digital format, so that the image may later be edited or otherwise processed. In the prior art, it is common to interpolate and compress the digital image data prior to storage. Manipulating the data before storing it posses certain disadvantages that are inherent in the procedures utilized heretofore in the prior art.
First, the process of interpolation may introduce irreversible changes in the digital image data. Interpolation is the process of correcting the data for errors that occur by virtue of the type of camera or sensor that is utilized within the camera. Therefore, the type of interpolation that is used, or the need for interpolation at all, is determined by the nature of the imaging process utilized. For example, it is common in the art to utilize digital sensors that contain charge-coupled devices (CCD) or metal oxide semiconductor (MOS) transistors. Within the sensor, the smallest resolvable full-color image component (xe2x80x9cpixelxe2x80x9d) is usually comprised of four separate sensors: two green, one blue, and one red. These sensors are used to produce three-color digital output. However, Interpolation is necessary to correct for distortions caused by the small, though finite distances, that separate the four individual sensors that make up each pixel. The result of this interpolation is often a great increase in the size of the original digital image; often this increase in data size is three-fold. Along with this increase in size, interpolation can compromise the integrity of the original data if performed prior to storage.
Second, after the step of interpolation, the digital image data is often compressed prior to storage. Compression is necessary often because of the increase in size after the interpolation function just discussed, as well as to facilitate transmission through systems of limited bandwidth, such as television systems. However, in compression methods commonly used, once a digital image has been compressed, it can never be restored to its original state. This is a major disadvantage if access to the original, uncompressed digital image data is ever desired.
The problems with the interpolation and compression of digital image data prior to storage manifest themselves as poor-quality output when viewed on a screen or printed. In fact, interpolation or compression techniques often create moirxc3xa9 patterns on fine-pitched fabrics, or result in the loss of detail and/or distortions along the edges or between fine lines in the subject matter.
In light of the above background, it is apparent that there is a need for a digital imaging storage and retrieval method that eliminates the problems associated with the interpolation and compression of digital image data.
Furthermore, in light of the above background, it would be advantageous for a digital imaging storage and retrieval system to be coupled with an active pixel sensor array.
A method according to the present invention for storing digital information from an image sensor array comprising the steps of: providing an image sensor array producing three-color output data at each of a plurality of pixel locations; providing a digital storage device coupled to the image sensor array; sensing three-color output data from the image sensor array; and storing the three-color digital output data as digital data in the digital storage device without performing any interpolation on the three-color output data. The storage step may be performed using a semiconductor memory device such as a random access memory or the like.
Another method according to the present invention utilizes the above method on an image obtained from an image sensor array further comprising a triple-junction structure where each pixel in the array measures each of the primary colors at the same location.
The method of the present invention may also optionally include the step of performing a lossless compression operation on the three-color digital output data prior to the step of storing the three-color digital output data in the digital storage device.